This invention relates to steam generators and particularly to steam generators for such uses as soil sterilization where only a very low steam pressure is necessary and the stringent requirements of the steam engineering code are inappropriate and unduly onerous.
Soil sterilization is one of a number of fields where there is need for a source of steam at relatively low pressure which can readily be transported to a location of use, and which is sufficiently free from the hazards normally accompanying steam generators to obviate the need for a stationary engineer in constant attendance.
The present invention comprises a generator in which a water tube structure is connected between a water header below it and a steam header above it. This structure comprises a plurality of portions, each of substantially annular configuration, which in practice either may constitute the successive turns of a tubular helix having its ends closed, or may comprise a plurality of coaxial, completely independent tubular rings or annuli. In either case, the structure has a horizontal axis, and the tops of all the portions are connected by independent conduits to the steam header above, while the bottoms of all the portions are connected, again by independent conduits, to the water header below.
The portions are closely but not tightly spaced axially, and baffle means are provided at each end. There is thus defined a combustion chamber, and an oil or other burner is arranged to direct a flame axially into the chamber through the baffle means at one end. For the most part, the products of combustion leave the chamber at the other end, but some of the products pass upwardly between the portions of the water tube structure. The baffle means is arranged so that after leaving the chamber, the principal portion of the combustion products is also deflected to pass around the steam header.
The components just described are mounted in a suitable housing with air inlet and outlet openings, fuel and water supply lines, the latter including a level control system, and a steam outlet line including a pressure relief valve. This gives a convenient, safe, self-contained unit which may be transported readily to a field location for supplying low pressure steam where it is needed.
Various advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and objects attained by its use, reference should be had to the drawing which forms a further part hereof, and to the accompanying descriptive matter, in which there are illustrated and described certain preferred embodiments of the invention.